SSH connection is refused outright

If ssh <user>@<ip> fails with "Connection refused" rather than a password prompt, the SSH server itself never started — the account/network are not the problem yet.

This particular Raspberry Pi OS image does not enable sshd by default even though SSH was turned on in Imager's Customisation step. It still ships the classic sshswitch.service mechanism as a fallback — the script itself lives at /usr/lib/raspberrypi-sys-mods/sshswitch if you want to confirm it's present on your image: on every boot it checks the boot partition for a file named ssh or ssh.txt and, if found, deletes it and force-enables sshd. From another computer, mount the microSD card's boot partition (the small FAT volume, bootfs) and create an empty file there:

touch /path/to/bootfs/ssh

Reinsert the card and power on — SSH should come up within seconds of boot, independent of any cloud-init timing.

tip

If you're working with more than one similar microSD card at a time, make sure you're editing the card that's actually in this device — see the card mix-up warning in SSH accepts connections, but every password is "Permission denied" in this section.